Ant Army Keeps NYC Streets Clean

New York City is often seen as a dirty, trash-ridden place, and you would think that its insects just add to the problem, but in actuality these arthropods help keep Manhattan streets clean, according to a new study.

Insect street sweepers such as ants eat a whopping 2,000 pounds of trash each year - that's the equivalent of 60,000 discarded hot dogs.

"This isn't just a silly fact," Dr. Elsa Youngsteadt explained in a release. "This highlights a very real service that these arthropods provide. They effectively dispose of our trash for us."

Youngsteadt and her colleagues from North Carolina State University, who were already studying urban insects, wanted to see just how much junk arthropods including insects and millipedes could consume, and whether they were more effective garbage men in certain areas compared to others.

The team placed two sets of food like hot dogs, potato chips and cookies on street medians and in parks. One set was easily accessible by arthropods alone, while another food pile could be eaten by arthropods and any other hungry animals nearby.

After 24 hours, researchers were surprised to see that ants and other insects alike ate two to three times more junk food on NYC sidewalks than those in parks - even though there was less biodiversity in the medians.

"We think this is because one of the most common species in the medians was the pavement ant (Tetramorium species), which is a particularly efficient forager in urban environments," Youngsteadt said.

And ants like Tetramorium aren't just taking care of a litter problem, but a pest problem as well. Manhattan is also filled with rats and pigeons that find discarded food and trash appetizing, and compete with arthropods for the loot. But with ants doing most of the eating and tidying, they're helping to keep rats and other pests at bay.